1) A GC/MS quantitative assay has been developed for pentamethylmelamine, and the method currently is being employed in pharmacokinetic studies in phase I clinical trials of the drug. 2) Studies of the metabolism, target organ alkylation, target cell cytotoxicity, and potential tumor-cell metabolism and cytotoxicity of 4-ipomeanol and related compounds are continuing. 3) Investigations of the role of the pulmonary Clara cell in lung toxicology and carcinogenesis are continuing. 4) Studies of the role of drug-metabolizing enzymes in drug-induced renal disease are ongoing. 5) Long-term toxicity and/or carcinogenicity studies with several furan derivatives and hydrazine derivatives have been initiated. 6) The roles of glutathione in cellular homeostasis is being investigated. 7) The role of cytochrome P-450 independent pathways of carcinogen activation are being studied, and 8) the role of membrane phospholipid methyltransferase enzymes in membrane physiology is being investigated.